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Johnathan Corgan
1c93fde672
The incoming-offer semaphore was global with no per-sender accounting and the permit was taken before any identity check, so one sender could hold every slot and deny rendezvous to everyone else. Each sender now has its own allowance with the global count kept as the outer bound. Note what this does and does not do: it raises the cost from one keypair to a small number of them, so a sender willing to spend throwaway identities can still saturate the pool at unchanged total offer rate. The signal freshness bound is only sound while the acceptance window stays strictly inside the replay window, or an offer evicted from the replay cache is still fresh enough to be accepted twice. The relation was stated in a comment and enforced nowhere. Config validation now rejects the bad combination at load, derived from the skew constant rather than a literal, and checked regardless of whether the feature is enabled so that turning it on later cannot surface an error at a surprising moment. The NAT lab config generator produced a combination the new rule rejects and is corrected in the same change. The punch-target filter shipped with no test that would fail if it were reverted. Loopback, link-local and multicast candidates and an oversized list are now covered, and the cap assertion is tightened from a bound to an equality. The private-range inclusion that LAN traversal depends on is pinned as a healthy path so a blanket ban cannot pass. Green: fmt, build, clippy and test --lib, 1533 passed.
NAT Lab Harness
Real Docker-based NAT traversal integration tests for the mainline FIPS Nostr/STUN bootstrap path.
This harness spins up:
- two FIPS nodes
- a local Nostr relay
- a local STUN server
- one or two Linux router containers performing NAT with
iptables
For the NAT scenarios, the node LAN interfaces are not attached to
Docker bridge networks. The harness creates explicit veth pairs and
moves them into the node and router namespaces after docker compose up
so every packet must traverse the router namespace.
It covers three scenarios:
cone: both peers behind explicit namespace/veth full-cone emulation, UDP traversal succeedssymmetric: both peers behind symmetric-style NAT, UDP traversal fails, TCP fallback succeedslan: both peers share a LAN subnet, LAN targets are preferred over reflexive addresses
NAT model notes
The harness does not rely on plain Docker MASQUERADE for the cone case.
cone- uses explicit full-cone emulation in the router namespace
- outbound UDP is
SNATed to the router WAN address while preserving the source port - inbound UDP to the router WAN address is
DNATed back to the single LAN host regardless of remote source
symmetric- uses UDP
MASQUERADE --random-fully - outbound mappings may be port-randomized and are only reopened by matching conntrack state
- uses UDP
This distinction matters because plain MASQUERADE is convenient source NAT, but it does not by itself model the "accept from any remote once mapped" behavior expected from a full-cone NAT.
Prerequisites
- Docker with Compose support
- locally built
fips-test:latest
Build the test image with:
./testing/scripts/build.sh
Run
Run all scenarios:
./testing/nat/scripts/nat-test.sh
Run one scenario:
./testing/nat/scripts/nat-test.sh cone
./testing/nat/scripts/nat-test.sh symmetric
./testing/nat/scripts/nat-test.sh lan
Layout
docker-compose.yml- relay/STUN/WAN topology plus container definitions
node/- node bootstrap wrapper that waits for the injected veth interface
router/- NAT router image and
iptablessetup
- NAT router image and
stun/- minimal STUN binding responder
relay/- local
strfryconfig
- local
scripts/generate-configs.sh- derives ephemeral identities and writes per-scenario FIPS configs
scripts/setup-topology.sh- injects and configures the NAT LAN
vethpairs in the container namespaces
- injects and configures the NAT LAN
scripts/nat-test.sh- boots the lab, waits for convergence, and asserts the resulting path
Assertions
-
cone- both nodes connect
- connected transport is UDP
- active link remote addresses are on the WAN NAT subnet
-
symmetric- NAT bootstrap does not establish a UDP link
- fallback converges
- connected transport is TCP via router-published WAN addresses
-
lan- both nodes connect
- connected transport is UDP
- active link remote addresses stay on the shared LAN subnet